Thermally actuated diffuser

ABSTRACT

A diffuser for a conditioned air system for buildings incorporates a self contained and integrated sensor actuator for varying the volume flow of conditioned air through the diffuser in response to changes in room air temperature. 
     The sensor actuator structure for sensing the room air temperature and for modulating the conditioned air flow is entirely contained within the diffuser structure and is powered directly by the changes in room air temperature without auxiliary equipment or power systems. 
     The self contained diffuser is fully adaptable to existing systems to provide either or both modulated cooling and modulated heating and also to supply modulated cooling with the capability of morning warm-up. 
     The diffuser is constructed to direct the air flow from the periphery of the diffuser and into the room at an angle and with a velocity which causes the air flow to have preferred aerodynamic characteristics so as to hug the ceiling and to avoid dumping.

CROSS REFERENCE TO RELATED APPLICATION

Pending U.S. Application Ser. No. 862,812 filed Dec. 21, 1977 by RobertL. Vance (and assigned to the same assignee as the assignee of thisapplication) discloses a thermally power actuator of the general kinddisclosed in this application.

BACKGROUND OF THE INVENTION

This invention relates to a conditioned air system for buildings.

This invention further relates to a diffuser unit for a conditioned airsystem, and in particular to a ceiling mounted diffuser unit for aconditioned air system which delivers a modulated, variable volume ofconditioned air to a room or other space in the building in response tochanges in the temperature of the air in that room or other space whichit conditions.

The invention also relates to an integrated sensor actuator which bothsenses temperature changes in the room and also provides the actuatingforce for varying the amount of air flow into the room in response tothe sensed temperature. The integrated sensor actuator generates theactuating force for varying the volume of air flow without the use ofany external or auxiliary systems or apparatus, (such as pneumatic air,duct pressure or electrical or hydraulic powered apparatus) forsupplying the force necessay to vary the volume of air flow.

The invention also relates to a diffuser construction which directs theoutflowing air from the diffuser into the room and along the adjacentceiling surfaces at an efficient aerodynamic angle and velocity so as tocause the air to hug the ceiling and to minimize the problems of dumpingof cold air in the parts of the room adjacent and below the diffuser.

The invention also relates to a diffuser which is constructed to operateon a low pressure differential to minimize noise and to conserve powerand energy of the related conditioned air system.

Dumping of cold air from a ceiling mounted outlet for a ceilng mountedconditioned air system has been a problem in the prior art. If thecooling air does not leave the ceiling outlet with sufficient velocityor at the proper angle of flow, the result can be large temperaturedifferentials between different areas and different levels in the room,and this can produce noticeable discomfort for the people in the room.

Most conditioned air distribution systems are set up to vary either thevolume or the temperature of the conditioned air flow in response to ameasurement of the temperature in the room. If the volume of theconditioned air flow is varied, the system is known as a variable airvolume system (in the terminology of the art). Many currentinstallations of conditioned air systems are using variable air volumesystems (rather than constant volume, variable temperature systems)because the variable air volume system offers a number of potentialoperating and cost advantages.

The conventional practice in the prior art has been to modulate thevolume flow of conditioned air in response to the air temperature in theroom to which the conditioned air is supplied. In most such cases, athermostat is used to sense the air temperature, and the thermostat isconnected to an actuator system for positioning a damper in the branchduct supplying the conditioned air outlet device for the room. Thetemperature sensing mechanism is usually located in a position which isremote from the conditioned air outlet, and an auxiliary system orapparatus (such as an pneumatically powered actuator or an electricallypowered or in some cases and hydraulicly powered actuator) is used toreposition the damper with changes in the room air temperature.

There are also actuating systems used in the prior art which are calledself contained systems, but such systems are self contained in the senseonly that they use the duct pressure to power and reposition the damper.

These prior art systems have presented a number of problems. They havebeen somewhat complex because of the need to interconnect the remotelylocated thermostat with the actuator apparatus. And the auxiliaryactuator apparatus has in itself often contributed unfavorably to thecomplexity and size and cost of the system.

It is a primary object of the present invention to avoid and to overcomethe problems of the prior art as described above.

It is a closely related object to construct an individually controlled,self contained, variable air volume diffuser which incorporates, as anintegral part of the diffuser, a unitary sensor actuator that isdirectly powered by the temperature of the air in the room and that doesnot require any auxiliary actuator system or apparatus for varying thevolume flow of conditioned air through the diffuser in response tochanges in the sensed room air temperature.

SUMMARY OF THE INVENTION

The diffuser of the present invention, in one particular embodiment,comprises an outer can which has a rectangular shaped lower part and ofa standard size and configuration so as to fit within a standard moduleof a modular ceiling. The upper part of the can has a circularconfiguration so as to fit within a branch duct of a conditioned airdistribution system of a building. The can sidewalls are inclined at anoutward angle for guiding the diffused air flow in the proper directionand with the desired flow velocity to cause the air flowing from theperiphery of the diffuser to hug the ceiling and to avoid dumping.

The diffuser also includes a central diffuser plate which coacts withthe sidewalls of the diffuser can to direct the conditioned air flow inthe way described above.

All of the operating structure for modulating the volume flow of theconditioned air through the diffuser is mounted on and carried by thediffuser plate.

The diffuser plate and associated structure are quickly and easilyinstalled and are removed from the diffuser can by four nuts whichretain the diffuser plate on bolts or studs extending down from thediffuser can.

In one embodiment of the invention the structure which modulates thevolume flow of conditioned air includes four louvers which are mountedby hinged connections in the edge portions of the diffuser plate. Eachlouver is moveable between a fully closed position (in which the outeredge of the louver engages the related inner surface of the sidwall ofthe can to block all flow through the diffuser) to a fully openedposition (in which the louver swings downwardly to permit the maximumvolume of conditioned air to flow through the diffuser). Each louveritself coacts with a related sidewall of the can to channel and toconfine the conditioned air flow in the desired aerodynamic directionand with the desired velocity to maximize the Coanda effect so that theflow of conditioned air from the diffuser does hug the ceiling asdescribed above.

Each vane is connected by a control rod to a louver control disc whichis mounted for rotation with a shaft extending centrally through thediffuser plate. The control rods are linked to the louver control discso that the louvers are fully closed at top dead center of each point ofconnection of a control rod to the control disc. As the control disc isrotated away from that top dead center position, and in eitherdirection, the louver is progressively opened. Rotation of the controldisc back toward top dead center position progressively returns thelouver toward the fully closed position.

This association of the control disc, central shaft and louver controlrods is used for modulated cooling when cooling air is supplied throughthe branch duct to the diffuser unit.

In this mode of operation the louvers can also be moved rapidly to afull open position (to permit the flow of warm air) by rotating thecontrol disc past top dead center and through an arc on the side of topdead center opposite that used for modulated control of the cooling airflow. Rotating the control disc in this direction then permits thelouvers to be subsequently moved toward a more closed position inresponse to an increase in room air temperature so as to then providemodulated heating.

The angular position of the control disc on the central shaft can alsobe varied to rotate the control disc far enough with respect to thecentral shaft to move the louvers to a full open position. The controldisc is then reconnected to the central shaft so that the diffuser willact as a normally closed diffuser for modulation of warm conditionedair. A sensed increase in the room air temperature will then have theeffect of moving the louvers toward a more closed position (rather thantoward a more open position as is the case when cooling air is suppliedthrough the diffuser).

This embodiment of the diffuser using louvers can therefore be installedand operated to provide four different modes of operation.

It can provide a fixed volume flow with the louvers set at a fixedangle.

It can provide modulated cooling of a cooling air flow in response tochanges in room air temperature.

It can provide the modulated cooling with a capability of changing to amodulated heating mode.

It can also provide modulated heating by controlling the volume flow ofwarm air in response to changes in the room air temperature.

In another embodiment of the diffuser structure, the modulation of theconditioned air flow is produced by two relatively rotatable plates.Each plate has a number of radially extending and circumferentiallyspaced slots or openings. The extent to which the sets of slots in thetwo discs are aligned determines the amount of conditioned air which ispermitted to flow through the plates and through the diffuser.

This embodiment of the invention provides the same four options ordegrees of control as described above for the louver construction,depending upon the initial positioning of the two relatively rotatableplates. Thus, this embodiment can provide a fixed slot alignment for apre-selected, constant volume of flow, or it can provide modulatedcooling, or it can provide a modulated cooling with the capability ofheating, or it can provide modulated heating.

The second embodiment can also preferably incorporate fixed openingperipheral slots which establish a minimum air flow stream along eachperipheral outlet edge of the rectangular shaped diffuser. This minimumair flow stream is required for ventilation in some conditioned airinstallations. The diffuser of the present invention utilizes thisminimum air flow stream to maximize the Coanda effect (described above)by entraining the modulated conditioned air flow (particularly at therelatively low volume flows of conditioned air) so that the relativelyhigh velocity flow of the minimum air flow stream tends to hold up andto prevent undesired damping of the modulated flow of conditioned air.

The minimum air flow stream also entrains a certain amount of room airto induce upward flow of room air to contact with the room airtemperature sensing structure of the diffuser mounted below the diffuserplate in the diffuser can.

The construction and mode of operation of both the embodiments of thediffuser of the present invention permit the diffuser to operate withrelatively low pressure differentials. This has the advantage ofsubstantially reducing turbulence and noise, and it has furtheradvantages of being efficient so that power and cost of operation of thesupply fan for the conditioned air system can be minimized.

It is an important feature of the present invention that the diffuser(in both embodiments described above) incorporates an integrated, sensoractuator for positioning the diffuser control structure to vary thevolume flow of conditioned air through the diffuser in response tochanges in room air temperature.

The sensor actuator is entirely self contained within the diffuserstructure and is powered directly by the changes in the sensed room airtemperature without auxiliary equipment or power systems.

In a specific embodiment of the present invention the sensor actuatorcomprises a coiled tube sensor filled with a temperature sensitivesubstance. Room air is induced to flow over the sensor so that increasesand decreases in the room air temperature cause corresponding increasesor decreases in the volume of the temperature sensitive substance. Anincrease in room air temperature causes an expansion of the temperaturesensitive substance. The expansion pushes an actuator rod in a directionto rotate the central control shaft in the diffuser unit to cause aresulting repositioning of the louvers or rotary disc as describedabove. The contraction of the temperature sensitive substance (as occurswhen the room air temperature decreases) permits a return spring toretract the actuator rod; and this moves the louvers or rotary disc inthe opposite direction.

The sensor actuator is mounted beneath the diffuser plate of thediffuser in a floating mounting which isolates the sensor actuator fromany heat transfer contact with the diffuser plate.

Diffuser apparatus and methods which incorporate the structure andtechnique described above and which are effective to function asdescribed above constitute specific objects of this invention.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in accompanyingdrawings which, by way of illustration, show preferred embodiments ofthe present invention and the principles thereof and what are notconsidered to be the best modes contemplated for applying theseprinciples. Other embodiments of the invention embodying the same orequivalent principles may be used, and structural changes may be made asdesired by those skilled in the art without departing from the presentinvention and the purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the bottom plan view of a part of a modular ceiling showing athermally actuated variable air column diffuser constructed inaccordance with one embodiment of the present invention and installed inone of the rectangular modules of the modular ceiling. In FIG. 1 part ofthe appearance plate has been partially broken away to show details ofthe diffuser plate, the louvers (or vanes), at the edges of the diffuserplate, the temperature sensor coil and related cooling actuator, thelouver control disc, and the linkage rods extending from the louvercontrol disc to the louvers.

FIG. 2 is a side elevation view taken along the line and in thedirection indicated by the arrows 2--2 in FIG. 1 and in FIGS. 3 and 4.

FIG. 3 is a fragmentary plan view taken along the line and in thedirection indicated by the arrows 3--3 in FIG. 2. FIG. 3 shows detailsof the cooling actuator and cooling actuator link arm in associationwith an outer sleeve which is connected to a heat actuator mountingplate shown in FIG. 4. FIG. 3 also illustrates, by the legends, thedirection of rotation of the louver control disc in the cooling mode andin the heating mode.

FIG. 4 is a fragmentary plan view taken along the line and in thedirection indicated by the arrow 4--4 in FIG. 2. FIG. 4 shows details ofa heat actuator mounting plate, a heat sensor, a heat actuator, a heatactuator link arm, and the association of the link arm with a shaftconnected to the louver control disc shown in FIG. 3.

FIG. 5 is an enlarged cross sectional view through the cooling actuatorand is taken along the line and in the direction indicated by the arrows5--5 in FIG. 3.

FIG. 6 is an enlarged cross sectional view through a temperatureadjustment mechanism for adjusting the controlling temperature range ofthe room temperature sensor. FIG. 6 is taken along the line and in thedirection indicated by the arrows 6--6 in FIG. 3. This mechanism alsoprovides for overload capacity if the system is exposed to excessivetemperatures.

FIG. 7 is a bottom plan view like FIG. 1 but showing another embodimentof the thermally actuated variable air volume diffuser constructed inaccordance with the present invention. The embodiment of the inventionshown in FIG. 7 incorporates a rotary and slotted plate construction formodulating the amount of air flow.

FIG. 8 is an elevation view taken along the line and in the directionindicated by the arrows 8--8 in FIG. 7. FIG. 8 also illustrates how thediffuser of the present invention (in both the illustrated FIG. 8embodiment and in the FIGS. 1-4 embodiment) causes the diffused air flowto hug the ceiling while preventing dumping.

FIG. 9 is a fragmentary plan view taken along the line and in thedirection indicated by the arrows 9--9 in FIG. 8.

FIG. 10 is a fragmentary elevation view in cross section and includesgenerally that part of the structure shown encircled by the arrows10--10 in FIG. 8. FIG. 10 shows the slots in the two rotary discsaligned for permitting air flow through the aligned slots.

FIG. 10 also illustrates details of the floating mounting of thetemperature sensor for isolating and insulating the sensor from thediffuser plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A thermally actuated, variable air volume diffuser constructed inaccordance with one embodiment of the present invention is indicatedgenerally by the reference numeral 21 in FIG. 1.

FIG. 1 is a bottom plan view looking upwardly at a room ceiling.

The ceiling, as illustrated in FIG. 1, is a modular ceiling comprising anumber of individual modules 23. The diffuser 21 of the presentinvention is installed in the ceiling in the place of one of the modules23.

The diffuser 21 distributes a variable volume of air to the room, orother space, from a branch duct, and the amount of air flowing throughthe diffuser 21 is modulated in response to changes in the airtemperature in the room, as will be described in detail below.

The branch duct is shown in FIG. 2 and is indicated by the referencenumeral 25. This branch duct 25 is in turn connected to a main supplyduct (not illustrated).

A supply fan is controlled to maintain a required pressure within themain duct system as, for example, by means of a conventional controlsystem which senses the static pressure in the main duct system andincreases or decreases the fan volume to maintain the static pressurewithin the control range. Each branch duct 25 may have its capacitycontrolled at the major points of distribution to maintain the requiredpressure at the diffuser 21, again by conventional and well knownapparatus and techniques.

It is an important feature of the present invention, as will bedescribed in more detail below, that the diffuser 21 operates at arelatively low pressure differential. This has the benefit of beingenergy and cost efficient, and it has the further benefit of minimizingthe noise produced by air flow through the diffuser.

As illustrated in FIGS. 1 and 2, the diffuser 21 comprises a diffusercan 27, an appearance plate 29, and a diffuser plate 31.

The diffuser plate serves both as a plate for directing the air flow andas a support structure for the operative components of the diffuser.

FIG. 8 shows how air (see arrow A) flowing from the branch duct 25 isdeflected (see arrows B) by the diffuser plate 31 outwardly to theperiphery of the diffuser can 27 for subsequent flow (see arrow C) downalong the inner surfaces 33 of the related, inclined sidewalls of thecan 27.

As will be described in greater detail below, this diffuser platedirected air flow induces a certain amount of room air (see arrows D) upthrough the appearance plate 29. This induced room air flows over asensor actuator assembly 71 described below and is mixed with theconditioned air and distributed from the four peripheral edges of thelower end of the can 27 (as indicated by the direction arrows E in FIG.8). The air leaving the periphery of the diffuser 21 is directed at anangle with respect to the adjacent ceiling panels 23 so as to provide amaximum Coanda effect and to thereby cause the diffused air to hug theceiling and to avoid dumping.

This mode of operation of the diffuser plate 31 and related diffuserstructure is produced by both the FIG. 1 and the FIG. 7 embodiments ofthe present invention and will be described in more detail below withspecific reference to the FIG. 7 embodiment.

The other function of the diffuser plate 31 (the function of serving asa support for the operative components of the diffuser 21) will now bedescribed.

As best illustrated in FIGS. 1 and 7, the diffuser plate is removableattached to the can 27 by four nuts 35 and corresponding bolts 37.

In the FIG. 1 embodiment four louvers or vanes 39 are connected byhinges 41 to the plate 31, and each louver 39 is moveable from a fullyclosed position (in which the outer edge of the louver engages theinside surface 33 as illustrated in FIG. 2) to a fully open position (asillustrated in FIG. 2) to a fully open position (as illustrated by thereference numeral 39A in FIG. 2).

The control of the movement of each louver 39 between the fully closedposition and the fully open position and all intermediate positions isproduced by a rod 43 and a louver control disc 45.

The louver control disc 45 is in turn connected to a shaft 47 by alocking nut 49 for rotation with the shaft 47.

As will be described in greater detail below, the locking nut 49 can beloosened, and the angle at which the plate 45 is connected to the shaft47 can be varied to provide for either modulated cooling (when coolingair is supplied through the branch duct) or to provide modulated heating(when warm air is supplied through the branch duct).

With continued reference to FIG. 2, the shaft 47 is mounted within asleeve 51. Under certain conditions of operation the shaft 47 and sleeve51 are rotated together and in unison. Under other conditions ofoperation, such as during morning warm-up as described in more detailbelow, a limited amount of relative rotation between the shaft 47 andthe sleeve 51 occurs.

The sleeve 51 is in turn mounted for rotation within the diffuser plate31 by a bushing or bearing 53.

A heat actuator mounting plate 55 is connected to the upper end of thesleeve 51 (as illustrated in FIG. 2).

A cooling actuator link arm 57 is connected to the mid part of thesleeve 51 by a locking nut 59.

The connections between the sleeve 51, the heat actuator mounting plate55 and the cooling actuator link arm 57 are such that these threeelements always move together as a rigid assembly.

A heat actuator linked arm 61 is connected to the upper end of the shaft47 as illustrated in FIG. 2. This is a rigid connection so that the heatactuator link arm 61, shaft 47 and louver control disc 45 always move asan integrated assembly.

As illustrated in FIG. 3, when the diffuser 21 is set up to provide amodulated cooling mode of operation, the louver control disc 45 isrotated from the normally closed position and in a clockwise direction(as indicated by the legend "cooling" in FIG. 3 to produce progressivelygreater cooling air flow) by progressively retracting the vanes 39 fromthe normally fully closed position to the maximum open position 39Ashown in FIG. 2. With the particular embodiment illustrated in FIGS.1-4, this movement to full open from full closed is produced by about30° of rotation of the louver control disc 45 as illustrated in FIG. 3.

In this modulated cooling mode of operation the louvers 39 can also bequickly and fully opened from a normally closed position (or any othermodulated cooling position) to permit the heating air to be suppliedthrough the diffuser 21 during a heating condition of operation. Thelouver control disc 45 is rotated counter clockwise (as indicated by thelegend "heating" in FIG. 3) to provide this opening of the louvers for amorning warm-up mode of operation.

Furthermore, and as will be described in greater detail below, thelocking nut 49 can be loosened and the relative angular position of thelouver control disc 45 with respect to the shaft 47 can be changed(again by approximately 30°) to rotate the louver control disc 45counter clockwise (as viewed in FIG. 3) with respect to the shaft 47 toan extent sufficient to move the louvers 37 to a normally full openposition 39 A. The locking nut 49 is then tightened to hold the louvercontrol disc 45 in this adjusted position and the diffuser 21 will thenprovide modulated heating as warm air is supplied through the branchduct 25 in response to changes in the sensed air temperature in theroom. That is, the vanes 37 will be moved, in a modulated way, from anormally full open position to a full closed position as the room airtemperature is increased to a certain level.

With the diffuser 21 set up as illustrated in FIGS. 2 and 3 to providemodulated cooling with cooling air supplied through the branched duct25, the movement of the louvers 39 and louver control disc 45 from thenormally fully closed position to modulated open positions (within thearc marked "cooling" in FIG. 3) is produced by a room air temperaturesensor actuator assembly indicated generally by the reference numeral 71in FIGS. 1, 2, and 3. The assembly 71 is mounted in a floating mountingbelow the diffuser plate 31 to isolate the assembly from heat transfercontact with the diffuser plate.

The rotation of the louver control disc to the other side of top deadcenter (and through the arc marked "heating" in FIG. 3) is provided by aduct heating air temperature sensor actuator assembly indicatedgenerally by the reference numeral 73 in FIG. 4. This movement of thedisc 45 moves the louvers 39 from a normally fully closed position to afull open position, in a rapid and coarse or unmodulated way, to providethe capability of morning warm-up with hot air in the duct.

Looking first at the construction of the room air temperature sensoractuator assembly 71 in FIG. 3, the assembly 71 comprises a coiled tubesensor 75, an actuator 77, a temperature range adjustment mechanism 79,a return spring 81, the cooling actuator link arm 57, a stop 83, and anoverload capacity or chamber 107.

The duct heating temperature sensor actuator assembly 73 is similar tothe room air temperature sensor actuator assembly in the make up of itscomponent parts. Thus, the assembly 73 (as illustrated in FIG. 4)comprises a coiled tube sensor 85, an actuator 87, a temperature rangeadjustment mechanism 89, a return spring 91, the heat actuator link arm61, a stop 93, and an overload capacity chamber.

It is an important feature of the present invention that room airtemperature sensor actuator assembly 71 is self contained, integrated,sensor actuator that both senses changes in the room air temperature and(at the same time and using the sensed room air temperature change asthe power source) modulates the volume of the conditioned air flow (byrepositioning the louvers 39 in response to the changes in room airtemperature) to provide the room or other space with the cooling (orwarm) air flow that is required to return the room air temperature tothe set point.

As best shown in FIGS. 5 and 6, the sensor tube coil 75 contains atemperature sensitive substance which expands or contracts withincreasing or decreasing room air temperatures. As the room air isinduced to flow upward (as indicated by the arrows D in FIG. 8) and intocontact with the outer surface of the coiled tube sensor 75, thetemperature sensitive substance .[.93.]. .Iadd.94 .Iaddend.within thetube is heated or cooled or maintained, as the case may be, to or at thetemperature of the room air so that this substance .[.93.]. .Iadd.94.Iaddend.continuously senses the room air temperature and any changes inthe room air temperature.

If the room air temperature is increasing, the substance .[.93.]..Iadd.94 .Iaddend.will expand, and this expansion forces an actuator rod95 outwardly (to the right as viewed in FIG. 5) of an inner cylinder 97of the actuator 77. This outward movement of the actuator rod 95 rotatesthe link 57 (see FIG. 3) in a clockwise direction against the bias ofthe return spring 81.

The sleeve 51 rotates with the link 57, and the heat actuator mountingplate 55 also rotates with the interconnected sleeve 51 and link 57.

Looking at FIG. 4, when the conditioned air flowing through the branchduct 25 is cooling air, the actuator rod 89 of the heat actuator 87 isfully retracted within the actuator 87 and is maintained in thatposition by the bias or force of the return spring 91. As a result,rotation of the heat actuator mounting plate 55, as will be describedbelow, causes the entire duct heating air temperature sensor actuatorassembly 73 to rotate in unison with rotation of the cooling actuatorlink arm 57. The rotation of the heat actuator link arm 61 thereforecauses the interconnected shaft 47 to rotate in unison with the sleeve51; and the louver control disc 45 is thus rotated directly by, and inthe same direction, and to the same extent, as the rotation of thecooling actuator link arm 57 in this mode of operation.

The temperature operating range can be adjusted by the mechanism 79.This mechanism 79 includes a temperature adjusting knob 101 which isthreaded on an end of a temperature adjusting rod 103. The rod 103 is inturn connected to a plug piston 105 which is spring biased inwardlywithin a cylinder 107 of the mechanism 79 by a compression spring 109.Turning the knob 101 in the direction to move the rod 103 outwardly ofthe cylinder 107 increases the volume within a chamber 111. Adjustmentof the knob in this direction therefore requires the material .[.93.]..Iadd.94 .Iaddend.to expand to a greater degree before any resultingmovement is produced on the actuator rod 95 of the actuator. In amodulated cooling mode of operation this adjustment raises thetemperature operating range. Adjustment of the nut 101 in the oppositedirection lowers the temperature operating range.

The mechanism 79 also provides overload protection. The compressionspring 109 is preloaded on assembly to a load which is in excess of anyloads exerted by the return spring 81 over the normal operating range ofthe diffuser. The rod 103 can shift axially through a spring retainernut 104 to accommodate expansion of the chamber volume 107 increaseresulting from any condition (thermal or mechanical).

The internal construction of the actuator 87 is the same as that of theactuator 77 shown in FIG. 5, and the internal construction of thetemperature adjusting mechanism 89 is the same as that of thetemperature adjusting mechanism 79 shown in FIG. 6.

The same temperature sensing substance is used in the coiled tube sensor85 as in the coiled tube sensor 75.

The preferred material for the temperature sensing substance .[.93.]..Iadd.94 .Iaddend.is a material that has a high coefficient of thermalexpansion and a low degree of compressibility. The material should alsobe sufficiently soft to permit a moderate size return spring to build upenough force to return the actuator rod within the cylinder 97 as thesensed temperature decreases and the material .[.93.]. .Iadd.94.Iaddend.contracts. One particular composition that has been foundsatisfactory is a medium weight grease with a high parafin content. Itis a product which is normally used primarily as a preservative (toprevent rust or corrosion) and also as a lubricant. The temperaturesensitive substance .[.93.]. .Iadd.94 .Iaddend.is preferably a greasewith about a 60% by volume parafin content. This composition minimizesproblems of entrainment of air in the course of filling the assembly 71,and it contains enough solid so that the build modulus is high and thereis almost no compressibility.

With reference now to FIG. 4, the duct heating air temperature sensoractuator assembly 73 is connected to the shaft 47 to cause rotation(upon actuation of the actuator 87) in a direction counter to thedirection of rotation of the shaft 47 produced by the sensing of thewarmer air in the room by the sensor actuator assembly 71. That is, anincreasing air temperature in the room (as sensed by the sensor actuatorassembly 71) rotates the shaft 47 in a direction to open the louvers 39to let more cooling air flow from the diffuser 21; but the sensing ofhot air within the branch duct 25 by the sensor actuator assembly 73rotates the shaft 47 and louver control disc 45 in the oppositedirection (counter clockwise and through top dead center as viewed inFIG. 3) and through the arc marked "Heating" until the heat actuatorlink arm 61 engaged the stop 93. This causes a coarse and rapid movementof the louvers 39 toward a full open position because the temperaturedifferential sensed by the sensor actuator assembly 73 is so large whenwarm-up air is blown into the duct 25.

This mode of operation is often desired for a morning warm-up to bringthe room up to the desired temperature after the air temperature in theroom has been permitted to fall substantially below the desiredtemperature, such as during a weekend when the room is not being used.In this condition of operation, and assuming the actuator 77 senses aroom air temperature below that at which any cooling air flow isrequired (because there is no lighting or people to raise the roomtemperature), the actuator 77 moves the louvers 39 to the full closedposition.

When hot air is then blown through the branch duct for a limited periodof time, usually about half an hour, just shortly before the start ofnormal working hours on a Monday morning, the heat actuator 87 inresponse to the sensed high temperature of the hot air (for example,110° F.) in the branch duct rotates the link arm 61 counter clockwisewith respect to the stationary heat actuator mounting plate 55 to movethe louvers 39 to the full open position and to permit the maximumamount of warming air to flow into the cold room to quickly bring theroom air temperature up to the desired range (say 50° to 72° F.).

If the room air temperature increases to the point where the temperaturegets into the controlling range of the sensor actuator 71, then thesensor actuator 71 thereafter provides modulated heating by moving thelouvers to a more closed position with increasing room air temperature.

However, if the sensor actuator 71 has initially positioned the louversin a partially opened position (rather than in a fully closed position,as described above) at the time warm was supplied to the diffuser, thenthe sensor actuator 73 moves the disc 45 in a direction to close thelouvers (at TDC) and then to reopen the louvers to a partially openposition.

After a timed interval the flow of hot air is discontinued and coolingair is again introduced into the branch duct. This causes the sensoractuator assembly 73 to retract the rod 89 fully within the actuator 87,and this in turn swings the louver control disc 45 back to the positionwhere the louvers 39 are modulated in the cooling range and under thecontrol of the room air temperature sensor actuator assembly 71.

The stop 93 is an eccentric mounted stop so that the effective stopposition of the piston rod can be varied by loosening a retainer screw113, and rotating the stop 93 to the desired position and thenretightening the retainer screw 113. This is a factory setting which isnot normally changed in the field.

The stop 83 is also an eccentric mounted stop like the stop 93.

As noted above, the room air temperature sensor actuator 71 can be usedto provide modulated heating with warming air supplied through thebranch duct 25, and this is accomplished by loosening the lock nut 49,rotating the louver control disc 45 sufficiently far (about 30° asillustrated in FIG. 3) to move the louvers 39 from the normally fullclosed position to a normally full open position 39A with the actuatorrod 95 fully retracted within the actuator 77. The locking nut 49 isthen turned down to lock the louver control disc 45 on the shaft 47 atthis position, and the sensor actuator assembly 71 then operates in amode of operation which modulates from normally full open to a fullclosed on the sensing of increasing temperatures within the selectedrange in the room air.

The FIGS. 1-4 embodiment as described above provides full flexibility ofmodulated cooling, modulated cooling with morning warm-up and modulatedheating.

For some applications no modulated heating or cooling is required, andin this case, the louvers 39 are set at a fixed angle in a fieldinstallation and the diffuser plate 31 is installed in the can 27without either the sensor actuator assembly 71 or the sensor actuatorassembly 73.

If it is subsequently desired to provide modulated cooling, then thiscan easily and quickly be done by removing just the four nuts 35,removing the installed diffuser plate 31, replacing it with a diffuserplate having the room air temperature sensor actuator assembly 71, and,if desired, also having the duct air temperature sensor actuatorassembly 73 for providing either just modulated conditioned air controlor modulated conditioned air control with the feature of override formorning warm-up.

A thermally actuated variable air volume diffuser constructed inaccordance with another embodiment of the present invention isillustrated in FIGS. 7-10. The parts of this embodiment of the diffuserwhich correspond to like parts in the embodiment of the diffuser shownin FIGS. 1-6 and described above are indicated by like referencenumerals.

The diffuser 21 shown in FIG. 7 is, like the diffuser 21 shown in FIG.1, constructed to have a standard 24 inch by 24 inch rectangularconfiguration at the lower end of the can 27 so that the diffuser willfit directly in the place of a standard ceiling module having thesedimensions.

This rectangular configuration also produces the effect of fourindividual 24 inch linear diffuser units (in view of the fact that thediffuser of the present invention directs the air outwardly along eachperipheral edge at relatively high velocity).

In certain conditioned air installations there are minimum ventilationrequirements, and the embodiment of the diffuser 21 shown in the FIGS.7-10 is especially well suited for such conditioned air applicationbecause it actually embodies two diffusers in one casing--a minimum,fixed flow volume diffuser and a variable flow volume diffuser.

The diffuser 21 as shown in FIGS. 8 and 9 incorporates a first controlplate 121 which extends across the entire inner area of the can 27between the inner surfaces 33 of the outwardly flared sidewalls of thecan. The control plate 121 has four downwardly turned flanges 123. Eachflange 123 coacts with the related inner surface 33 to define a channelor slot 125. The slots 125 provide a primary air path which permits aminimum air volume of relatively high velocity air to be continuouslydiffused along the perimeter of the diffuser 21.

The control plate 121 also has a number or radially extending andcircumferentially spaced apart slots 127. As illustrated in FIG. 8 thevariable air volume flow (see the arrow C) must pass through thesecontrol slots 127.

The amount of conditioned air which is permitted to pass through theslots 127 is regulated by a second control plate 129 having radiallyextending and circumferentially spaced apart slots 131 which can bebrought into full registery with the slots 127 or which can be rotatedinto positions in which the slots 127 are partially or completelyblocked off.

The second control plate 129 is connected to the shaft 47 by a lockingnut 133 (see FIG. 8) so that the plate 129 rotates in unison withrotation of the shaft 47. The shaft 47 is in turn rotated in response tothe torque exerted by the link 57 (see FIG. 7) under the control of theroom air temperature sensing actuator 77 and the return spring 81.

The operation of these components in FIG. 7 is substantially the same asthe operation of the correspondingly numbered components shown in FIG. 3and described above, except for the fact that in the FIG. 7 embodiment aduct heating air temperature sensing actuator assembly (like that shownin FIG. 4) has not been illustrated as incorporated in the FIGS. 7-10embodiment. However, such a duct heating air temperature sensor actuatorassembly and related structure can be added to the diffuser shown inFIGS. 7-10 in the same way that it has been illustrated and described asincorporated in the diffuser illustrated in FIGS. 1-6.

Also, the angular orientation of the second control plate 129 withrespect to the shaft 47 (and with respect to the first control plate121) can be varied to change the mode of operation from a normallyclosed-modulated opening positioning of the slots 127 and 131 (in thecooling mode) to a normally open modulated closing positioning of theslots 127 and 131 (in a heating mode).

The shift of operations from one mode to the opposite mode (that is, theshift from going normally closed to normally open as one mode andshifting from that to the other mode which is going from normally opento closed) is dependent upon the geometrical arrangement of having thesecond control plate 129 set with edges of the slots 127 and 131 alignedin what is in effect a top dead center alignment with the slots 127fully closed by spaces between the slots 131. This mode of operation ofthe second control disc 129 is essentially the same as the positioningof the louver control disc 45 at the top dead center position with thelouvers 39 fully closed in the FIGS. 1-4 embodiment as described above.

Assuming the second control plate 129 is positioned and clamped by thelocking nut 133 to go from normally closed to open in a cooling modewhen cooling air is supplied through the branch duct 25, a sensing of anincreasing air temperature in the room will cause the cooling actuator77 to rotate the second control disc 129 in a direction to increase theamount of registery between the slots 127 and 131 to permit a greatervolume of cooling air to flow through the slots 127.

When the modulated air volume flowing through the slots 127 isrelatively low, the relatively high velocity of the minimum air flowthrough the slots 125 helps to insure that the desired clinging effectis provided in the mixture of the two air flows leaving the diffuserunit.

It should be noted that in the FIGS. 1-4 embodiment when the louvers 39start to open a relatively high velocity energy is produced right awayin the conditioned air flow to keep the air up, regardless of thevolume.

In the FIGS. 7-10 embodiment the relatively high velocity of the minimumair flow produces another beneficial effect because it maintains theinduction effect illustrated by the arrows D in FIG. 8. The same energythat causes the diffused air flow to cling to the ceiling and to preventdumping also assures that there is enough energy produced for theinduction needed for proper sensing of the room air temperature.

As best illustrated in FIG. 10 the coiled sensor tube 75 is heldsuspended beneath the diffuser plate 31 by a floating mounting 135 whichpermits the induced room air to flow over and around all surfaces of thetube sensor 75 and which also isolates and insulates the tube sensor 75from any heat transfer contact with the diffuser plate 31.

While we have illustrated and described the preferred embodiments of ourinvention, it is to be understood that these are capable of variationand modification, and we therefore do not wish to be limited to theprecise details set forth, but desire to avail ourselves of such changesand alterations as fall within the purview of the following claims.

We claim:
 1. A diffuser of a kind used to regulate the volume flow ofconditioned air from a duct to a room or other space comprising,(a) flowcontrol means for varying the size of an opening in the diffuser toregulate the volume flow of conditioned air from the duct through thediffuser and to the room or other space, and (b) sensor actuator meansoperatively associated with the flow control means and responsive toboth room air temperature and to duct air temperature for(1) modulatingthe flow control means in a normally closed to open mode of operation inresponse to changes in room air temperature when cooling air is suppliedthrough the duct, and (2) modulating the flow control means in anormally opened to close mode of operation when warm air is suppliedthrough the duct said sensor actuator means including a first sensoractuator positioned to sense only room air temperature and a secondsensor actuator positioned to sense only duct air temperature, said flowcontrol means including a .[.rotatable.]. .Iadd.movable .Iaddend.controlelement, and wherein the first sensor actuator is connected to.[.rotate.]. .Iadd.move .Iaddend.the control element in one direction inresponse to increasing room air temperature and the second sensoractuator is connected to .[.rotate.]. .Iadd.move .Iaddend.the controlelement in an opposite direction in response to increasing duct airtemperatures.
 2. A diffuser of a kind used to regulate the volume flowof conditioned air from a duct to a room or other space andcomprising,flow control means for varying the size of an opening in thediffuser to regulate the volume flow of conditioned air from the ductthrough the diffuser and to the room or other space, first sensoractuator means responsive to room air temperature and operativelyassociated with the flow control means for modulating the flow controlmeans in a normally closed to open mode of operation in response tochanges in room air temperature when cooling air is supplied through theduct, second sensor actuator means responsive to duct air temperatureand operatively associated with the flow control means for moving theflow control means to a full open position in response to the sensing ofwarm air in the duct, a fixed diffuser plate, said flow control meansincluding a sleeve mounted for .[.rotation.]. .Iadd.movement .Iaddend.inthe fixed diffuser plate and a shaft mounted for .[.rotation.]..Iadd.movement .Iaddend.within the sleeve, and wherein the first sensoractuator means are connected to .[.rotate.]. .Iadd.move .Iaddend.thesleeve and the second sensor actuator means are connected to.[.rotate.]. .Iadd.move .Iaddend.the shaft.
 3. A diffuser forcirculating conditioned air into a room from a ceiling location withinthe room and comprising,an outer can defining an air flow path, said canhaving an air discharging outlet, flow directing means located withinthe can and having a configuration to cause the air flow to be directedlaterally outwardly from the air discharge outlet at a narrow angle withrespect to the adjacent ceiling, volume flow regulating means mounted inthe can and movable to vary the volume flow of conditioned air throughthe diffuser, a diffuser plate located in the can for receivingcirculated room air along the underside of the diffuser plate and havingan upperside which causes all the conditioned air to flow through theair discharge outlet, sensor actuator means mounted on the underside ofthe diffuser plate and effective both to sense changes in the room airtemperature and to actuate the movable volume flow regulating meansdirectly from power produced by a change in the sensed room airtemperature, and wherein the volume flow regulating means areoperatively associated with the flow directing means to maintainsufficient velocity energy in the air flow through the air dischargeoutlet that the air flow hugs the ceiling and avoids dumping at allvolumes of flow through the diffuser, and wherein the diffuser plate isa rectangular plate, said flow directing means include a vane extendingalong each edge of the diffuser plate and connected to the diffuserplate by a hinge connection so as to permit swinging movement of thevane about the hinge connection and toward and away from an inner,adjacent surface of the can to vary the volume flow with changes inangular position of the vane and wherein the volume flow regulatingmeans include a .[.rotatable.]. .Iadd.movable .Iaddend.control elementmounted for .[.rotation.]. .Iadd.movement .Iaddend.on the diffuser plateby the sensor actuator means and having linkages connecting the.[.rotatable.]. .Iadd.movable .Iaddend.control element with each of thevanes for repositioning the vanes with .[.rotation.]. .Iadd.movement.Iaddend.of the control element by the sensor actuator means.
 4. Adiffuser for circulating conditioned air into a room from a ceilinglocation within the room and comprising,an outer can defining an airflow path, said can having an air discharge outlet, flow directing meanslocated within the can and having a configuration to cause the air flowto be directed laterally outwardly from the air discharge outlet at anarrow angle with respect to the adjacent ceiling, volume flowregulating means mounted in the can and movable to vary the volume flowof conditioned air through the diffuser, a diffuser plate located in thecan for receiving circulated room air along the underside of thediffuser plate and having an upperside which causes all the conditionedair to flow through the air discharge outlet, sensor actuator meansmounted on the underside of the diffuser plate and effective both tosense changes in the room air temperature and to actuate the movablevolume flow regulating means directly from power produced by a change inthe sensed room air temperature, and wherein the volume flow regulatingmeans are operatively associated with the flow directing means tomaintain sufficient velocity energy in the air flow through the airdischarge outlet that the air flow hugs the ceiling and avoids dumpingat all volumes of flow through the diffuser, and wherein the volume flowregulating means include a first, fixed plate having a plurality ofopenings for permitting flow of conditioned air through the openings anda second, control plate connected for .[.rotation.]. .Iadd.movement.Iaddend.by the sensor actuator means and effective to progressivelycover and uncover the openings in the first plate from full open to fullclosed as the second, control plate is .[.rotated.]. .Iadd.moved.Iaddend.by the sensor actuator means.